FTM needs help quick!!

Bailey

Hey there FTM here.. My baby girl will be 5 weeks old tomorrow and has been on similac pro sensitive since birth. I unfortunately was not able to nurse since my milk never came in. The last week or so, she has been spitting up a lot, like I can not keep burp rags clean. Then I noticed she was constipated, having solid poops and being a little fussy trying to pass them. I took her to her dr yesterday and he recommended switching her to similac total comfort or similac for spit up and giving her one ounce of pedialite in between feedings.

My question is, has anyone dealt with constipation yet with their newborn? What do I do? Which formula do I go with and how do I go about switching her without making her feel bad? I’m so lost and it’s killing me to see her hurt.